Acrylonitrile-butadiene-styrene (hereinafter referred to as ABS) resin has superior properties such as superior impact resistance, chemical resistance, processability and surface gloss, thus being broadly used in office machines, electrical and electronic products, automobile interior materials, toys, miscellaneous goods, and the like.
Recently, as interest on hygiene is increasing, research into ABS resin having antibacterial characteristics to inhibit bacterial contamination and bacteria proliferation due to contact is actively underway. Accordingly, various methods to provide antibacterial characteristics are suggested. As a most general method, there is a method of adding an antimicrobial agent to a resin. Used antimicrobial agents may be greatly classified into an organic antimicrobial agent and an inorganic antimicrobial agent.
An inorganic antimicrobial agent is generally prepared by substituting an inorganic substance such as zeolite, calcium phosphate, zirconium phosphate, or silica gel with metallic ions having anti-bacterial function such as silver, zinc, or copper. Such an inorganic antimicrobial agent is currently utilized in various fields such as plastic products, paper, or textile. However, so as to provide generally satisfied antibacterial characteristics through addition of the inorganic antimicrobial agent, the inorganic antimicrobial agent should be added in a large amount. In this case, the large amount of the antimicrobial agent may cause discoloration and property deterioration of a resin, and production costs increase.
For example, Korean Patent Laid-Open Publication No. 2006-0076792 suggests a method of providing antibacterial characteristics by adding silver nanoparticles, as an inorganic antimicrobial agent, to an ABS-based transparent resin. However, production costs greatly increase due to expensive silver nanoparticles. In addition, toxicity to the human body of the metal ions is being recently reported, and thus, attempts to limit use thereof have been continuously made.
An organic antimicrobial agent may be re-classified into a unimolecular antimicrobial agent having a small molecular weight and a polymeric antimicrobial agent. The unimolecular organic antimicrobial agent having a small molecular weight has superior short-term antibacterial characteristics, but persistence of antimicrobial activity thereof is very poor. In addition, use of the unimolecular organic antimicrobial agent is limited due to acute toxicity to the human body. On the other hand, the polymeric antimicrobial agent has advantages such as increased antibacterial activity, reduced toxicity to the human body, and extended persistence of antimicrobial activity, compared to an existing unimolecular antimicrobial agent having a small molecular weight. However, such a polymeric antimicrobial agent also has poor melt-kneadability to a resin, particularly an ABS-based thermoplastic resin. Accordingly, when the polymeric antimicrobial agent is melt-kneaded with the ABS-based thermoplastic resin by means of an extruder, or the like to prepare an antibiotic ABS-based thermoplastic resin, mechanical properties of a prepared thermoplastic resin are greatly decreased.
Therefore, so as to address the aforementioned problems, there is a need for research into ABS-based thermoplastic resin having superior antibacterial characteristics without decrease of mechanical properties due to a polymeric antimicrobial agent uniformly dispersed in a thermoplastic resin.